// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_SOCKET_SOCKS5_CLIENT_SOCKET_H_
#define NET_SOCKET_SOCKS5_CLIENT_SOCKET_H_

#include <stddef.h>
#include <stdint.h>

#include <memory>
#include <string>

#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "net/base/address_list.h"
#include "net/base/completion_callback.h"
#include "net/base/net_errors.h"
#include "net/dns/host_resolver.h"
#include "net/log/net_log.h"
#include "net/socket/stream_socket.h"
#include "url/gurl.h"

namespace net {

class ClientSocketHandle;
class BoundNetLog;

// This StreamSocket is used to setup a SOCKSv5 handshake with a socks proxy.
// Currently no SOCKSv5 authentication is supported.
class NET_EXPORT_PRIVATE SOCKS5ClientSocket : public StreamSocket {
public:
    // |req_info| contains the hostname and port to which the socket above will
    // communicate to via the SOCKS layer.
    //
    // Although SOCKS 5 supports 3 different modes of addressing, we will
    // always pass it a hostname. This means the DNS resolving is done
    // proxy side.
    SOCKS5ClientSocket(std::unique_ptr<ClientSocketHandle> transport_socket,
        const HostResolver::RequestInfo& req_info);

    // On destruction Disconnect() is called.
    ~SOCKS5ClientSocket() override;

    // StreamSocket implementation.

    // Does the SOCKS handshake and completes the protocol.
    int Connect(const CompletionCallback& callback) override;
    void Disconnect() override;
    bool IsConnected() const override;
    bool IsConnectedAndIdle() const override;
    const BoundNetLog& NetLog() const override;
    void SetSubresourceSpeculation() override;
    void SetOmniboxSpeculation() override;
    bool WasEverUsed() const override;
    bool WasNpnNegotiated() const override;
    NextProto GetNegotiatedProtocol() const override;
    bool GetSSLInfo(SSLInfo* ssl_info) override;
    void GetConnectionAttempts(ConnectionAttempts* out) const override;
    void ClearConnectionAttempts() override { }
    void AddConnectionAttempts(const ConnectionAttempts& attempts) override { }
    int64_t GetTotalReceivedBytes() const override;

    // Socket implementation.
    int Read(IOBuffer* buf,
        int buf_len,
        const CompletionCallback& callback) override;
    int Write(IOBuffer* buf,
        int buf_len,
        const CompletionCallback& callback) override;

    int SetReceiveBufferSize(int32_t size) override;
    int SetSendBufferSize(int32_t size) override;

    int GetPeerAddress(IPEndPoint* address) const override;
    int GetLocalAddress(IPEndPoint* address) const override;

private:
    enum State {
        STATE_GREET_WRITE,
        STATE_GREET_WRITE_COMPLETE,
        STATE_GREET_READ,
        STATE_GREET_READ_COMPLETE,
        STATE_HANDSHAKE_WRITE,
        STATE_HANDSHAKE_WRITE_COMPLETE,
        STATE_HANDSHAKE_READ,
        STATE_HANDSHAKE_READ_COMPLETE,
        STATE_NONE,
    };

    // Addressing type that can be specified in requests or responses.
    enum SocksEndPointAddressType {
        kEndPointDomain = 0x03,
        kEndPointResolvedIPv4 = 0x01,
        kEndPointResolvedIPv6 = 0x04,
    };

    static const unsigned int kGreetReadHeaderSize;
    static const unsigned int kWriteHeaderSize;
    static const unsigned int kReadHeaderSize;
    static const uint8_t kSOCKS5Version;
    static const uint8_t kTunnelCommand;
    static const uint8_t kNullByte;

    void DoCallback(int result);
    void OnIOComplete(int result);
    void OnReadWriteComplete(const CompletionCallback& callback, int result);

    int DoLoop(int last_io_result);
    int DoHandshakeRead();
    int DoHandshakeReadComplete(int result);
    int DoHandshakeWrite();
    int DoHandshakeWriteComplete(int result);
    int DoGreetRead();
    int DoGreetReadComplete(int result);
    int DoGreetWrite();
    int DoGreetWriteComplete(int result);

    // Writes the SOCKS handshake buffer into |handshake|
    // and return OK on success.
    int BuildHandshakeWriteBuffer(std::string* handshake) const;

    CompletionCallback io_callback_;

    // Stores the underlying socket.
    std::unique_ptr<ClientSocketHandle> transport_;

    State next_state_;

    // Stores the callback to the layer above, called on completing Connect().
    CompletionCallback user_callback_;

    // This IOBuffer is used by the class to read and write
    // SOCKS handshake data. The length contains the expected size to
    // read or write.
    scoped_refptr<IOBuffer> handshake_buf_;

    // While writing, this buffer stores the complete write handshake data.
    // While reading, it stores the handshake information received so far.
    std::string buffer_;

    // This becomes true when the SOCKS handshake has completed and the
    // overlying connection is free to communicate.
    bool completed_handshake_;

    // These contain the bytes sent / received by the SOCKS handshake.
    size_t bytes_sent_;
    size_t bytes_received_;

    size_t read_header_size;

    bool was_ever_used_;

    HostResolver::RequestInfo host_request_info_;

    BoundNetLog net_log_;

    DISALLOW_COPY_AND_ASSIGN(SOCKS5ClientSocket);
};

} // namespace net

#endif // NET_SOCKET_SOCKS5_CLIENT_SOCKET_H_
